Anthraquinone functionalized carbon composite electrode: Application to ammonia sensing

A simple strategy has been used to covalently modify the glassy carbon spheres with anthraquinone moieties through the diazonium salt reduction. The derivatized glassy carbon spheres were used to modify the basal plane pyrolytic graphite electrode by immobilizing them on its surface and examining its electrochemical behaviour. The composite electrode has been used to detect trace level ammonia in the concentration range 5 à 10-8 to 3 à 10-5 M and it was successfully applied to detect low levels of ammonia present in natural samples like urine and soil. © 2011 Elsevier B.V. All rights reserved

A new rhodamine B based fluorometric chemodosimeter for Cu2+ ion in aqueous and cellular media

A simple, sensitive and selective fluorescent chemo dosimeter rhodamine B phenyl hydrazide (RBPH) for Cu2+ was proposed. This probe is non fluorescent and colorless but exhibits fluorescent enhancement at 580 nm and displayed color change from colorless to pink for Cu2+ in the pH range 1-6. Fluorescence microscope experimental results reveals that this chemo sensor is cell permeable and can be used for fluorescence imaging of Cu2+ ions in living cells. This probe can detect Cu2+ with good linear relationships from 10 to 100 nM with r=0.99971 then limit of detection was found to be 0.015 nM with +/- 0.91% RSD at 10 nM concentrations. 2013 Elsevier B.V. All rights reserved

Determinants of Corporate Risk Disclosure in Annual Reports of UK Companies

The dissertation was focused on understanding the determinants of corporate risk disclosure in annual reports of UK companies. There were three key objectives to the research: (1) evaluate the determinants of narrative disclosure concerning risk management and internal control in the UK companies that is valuable to policy makers, (2) explain how companies disclose their financial information to various stakeholders – users, employees, government and clients among others, and (3) evaluate the knowledge resulting from the research and identify hints for future regulation and provide an impetus for more empirical research. The dissertation pursued a qualitative research based on secondary research. The summary findings and conclusions include the following: • Understanding motivations of firms in pursuing greater corporate risk disclosure. Firms have different motivations in providing increased disclosure and these include: (1) increased valuation, (2) better pricing of inputs, and (3) target specific investors. • Identifying the possible factors that drive the decisions of firms and which could be similar to own firms. Sector-specific rationale are important and, in the case of financial services firms, providing information on the illiquid assets and the amount written down are important particularly in the near-term where investors are searching for information. • Determine the best course of action related to corporate risk disclosures. Each firm will need to decide on the best course of action but certainly, some of the key principles in terms of disclosures, particularly for corporate risk, include the following: (1) provide increased transparency to the corporate risk management and internal controls processes and systems to provide investors and other stakeholders comfort and understanding, (2) ensure enough relevant information is provided to prevent any market rumours or speculation affect the business, and (3) ensure that the right individuals are in place and have the capability and skills to effectively perform the tasks. The dissertation showed that financial services firms provided greater disclosure of information in their annual reports versus retail sector firms

A Fluorescent Chemodosimeter for Hg2+Based on a Spirolactam Ring-Opening Strategy and its Application Towards Mercury Determination in Aqueous and Cellular Media

A novel fluorescent chemosensor rhodamine B phenyl hydrazide (RBPH) for Hg2+ was designed and synthesized. This probe is highly sensitive, selective, and irreversible for Hg2+ and exhibits fluorescent response at 580 nm. RBPH also displayed detectable color change from colorless to pink upon treatment with Hg2+. This property has been utilized as naked eye detection for Hg2+ in various industrial samples. Fluorescence microscopic experiments demonstrated that this chemosensor is cell permeable and can be used for fluorescence imaging of Hg2+ in cellular media. This probe can detect Hg2+ with good linear relationships from 1 to 100 nM with r = 0.99983 and the limit of detection were found to be 0.019 nM with ± 0.91 % RSD at 10 nM concentrations

Pharmaceutical electrochemistry: the electrochemical oxidation of paracetamol and its voltammetric sensing in biological samples based on screen printed graphene electrodes.

We present a sensitive, fast and unmodified sensor for the electrochemical detection of paracetamol. The electrochemical behaviours of paracetamol on screen printed graphene electrodes were investigated for the first time by cyclic voltammetry. The results showed that the screen printed graphene electrodes revealed exceptional electrocatalytic activity to paracetamol. The response showed by this sensor was enhanced when it was compared to the bare screen printed electrodes. When Screen Printed Graphene Electrodes were compared to bare SPE, it was shown that the response with graphene was greater than without. This is due to its unique characteristics physical and chemical, pi-pi interactions and a strong adsorptive capability. In this manuscript, the effect of supporting electrolyte, pH and scan rate were also investigated. The oxidation peak current was linearly proportional to the concentration of paracetamol in the range from 0.1 to 50 mM with a limit of detection of 20nM based on (3-s/slope), under the optimum conditions. The proposed method was successfully applied to paracetamol determination in in biological samples such as human oral fluid

Electrochemical determination of chemical oxygen demand using Ti/TiO2 electrode.

To overcome the shortcomings of the conventional potassium dichromate method (PDM) for monitoring chemical oxygen demand (COD) of waters, many efforts have been made on developing quick and environment-friendly techniques. Among all alternatives, electrochemical (EC) techniques are very competitive due to their relatively simple devices and quickness. A number of electrodes have been fabricated to investigate electrochemical determination of COD. However, little work has been reported on Ti/TiO2 based electrode for this purpose. In the present work, Ti/Ti/TiO2 electrode was simply prepared by anodic oxidation of pure titanium. Aqueous solutions of potassium hydrogen phthalate and phenol were electrolyzed by chronocoulometry in a three-electrode system with Ti/Ti/TiO2 as working electrode (anode). Organic compounds were electrochemically oxidized on Ti/Ti/TiO2 electrode by hydroxyl radicals and the released electrons were recorded and transferred to currents. The electric currents were proportional to the COD values of the water samples being investigated. Based on data of COD values and corresponding currents, a linear regression equation was obtained for a certain kind of waste water. With the regression equation, current of an unknown water sample was transferred to its COD value. Conditions for the presented EC method were set up as cell voltage 2.0V v.s. SCE and pH 7.0. The linear range of COD was of about 25~530 mg/L. COD values of real waste water samples were measured by Ti/Ti/TiO2 electrode and the relative errors were all in the range of ±8% compared with data determined by conventional PDM. The electrochemicalmethodology was successfully applied to evaluate COD in waste water

A novel mixed matrix membrane of phenolphthalein hydrazide and polysulfone for the detection of copper ions in environmental water samples.

The novel membrane test strip of phenolphthalein hydrazide (PH)-polysulfone has been designed and demonstrated for Cu2+ ions detection. Before finding performance of membrane the studies with PH alone has been performed. Aqueous solutions of PH are colorless, but upon interaction with Cu2+ ions become pink (when 8.2 ≤ pH ≥ 12). The colorimetric change is initiated by the coordination of Cu2+ with PH as a polydentate ligand, opening the spirolactam ring that subsequently hydrolyses releasing phenolphthalein (P). Further membrane was preloaded with PH that could be used as a simple, low cost, and portable sensor for Cu2+ ions in environmental water samples. Given the detection limits of this sensor, a maximum response would warn the tester that Cu2+ concentrations were above safe drinking regulation values. Approximate concentrations can be determined via a color comparison chart. Different metal ions were tested in order to determine the chemodosimeters specificity, of the 12 tested ions only Hg2+ induced a similar molecular transformation (i.e., PH to P). The chemodosimeter allows the quantification of Cu2+ ions in the linear dynamic range of 0–22 μM. The Sandell sensitivity, limit of detection, limit of quantification, and relative standard deviation were found to be 0.276 μg/mL/cm2, 0.279 μM, 1.674 μM, and 0.682% respectively

Adsorption removal of methylene blue from aqueous solution on carbon-coated Fe3O4 microspheres functionalized with chloroacetic acid.

We report the preparation and employability of carbon-coated Fe3O4 (Fe3O4/C) microspheres functionalized with chloroacetic acid (CAA) for the removal of methylene blue (MB) in aqueous solution. The prepared magnetic microspheres (Fe3O4/C-CAA) were characterized by the following techniques: X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectrometer, vibrating sample magnetometry, and Brunauer-Emmett- Teller. The characterization results showed that Fe3O4/C microspheres were modified by CAA without any phase change. Fe3O4/C-CAA microspheres have higher adsorption capacity for MB compared to Fe3O4/C microspheres. The Langmuir, Freundlich, and Temkin adsorption models were applied to describe the equilibrium isotherms, and the Langmuir adsorption model fitted well with the equilibrium data. The pseudo-first-order and pseudo-secondorder kinetic models were used to describe the kinetics data. However, the pseudo-second-order kinetic model fitted better with the adsorption kinetics data

Optimization and Numerical investigation of organic dye degradation using Response Surface by green synthesized ZrO2 nanoparticles and its antibacterial activity

In this work, the tetragonal Zirconium oxide (ZrO2) nanoparticles (NPs) were successfully synthesized by solution combustion method using Zirconium (IV) oxynitrate hydrate as the metal precursor and an oxidizer, Basella alba raw extract at 6000C. In this study, natural fuel is used to avoid harmful chemical fuels that may pollute the environment during combustion. The impact of the fuel-to-oxidant molar ratio on the surface morphological features of nanocrystalline zirconia particles has been documented. We investigated the Physico-chemical properties of the ZrO2 NPs via thorough characterizations like XRD, EDS, SEM, TEM, FTIR, UV-Vis, and BET. ZrO2 NPs exhibit perfect photocatalytic degradation activity towards Evans blue, a toxic dye. The influence of contact time, initial dye concentration, and pH were among the independent variables used in the study. The Response Surface Model (RSM) was used to optimize and describe the interdependencies of the different variables. The method was evaluated using the Box-Behnken design (BBD). A second-order polynomial model was used to properly understand the experimental results, and the effectiveness of the chosen model was verified by the strong agreement in determination coefficient values. ZrO2 NPs also exhibit good antibacterial activity on Gram-negative Klebsiella pneumoniae and Gram-positive bacteria, Bacillus subtilis

The control of reproductive physiology and behavior by gonadotropin-inhibitory hormone

Gonadotropin-releasing hormone (GnRH) controls the reproductive physiology and behavior of vertebrates by stimulating synthesis and release of gonadotropin from the pituitary gland. In 2000, another hypothalamic neuropeptide, gonadotropin-inhibitory hormone (GnIH), was discovered in quail and found to be an inhibiting factor for gonadotropin release. GnIH homologs are present in the brains of vertebrates, including birds, mammals, amphibians, and fish. These peptides, categorized as RF amide-related peptides (RFRPs), possess a characteristic LPXRF-amide (X = L or Q) motif at their C-termini. GnIH/RFRP precursor mRNA encodes a polypeptide that is possibly cleaved into three mature peptides in birds and two in mammals. The names of these peptides are GnIH, GnIH-related peptide-1 (GnIH-RP-1) and GnIH-RP-2 in birds, and RFRP-1 and RFRP-3 in mammals. GnIH/RFRP is synthesized in neurons of the paraventricular nucleus of the hypothalamus in birds and the dorsomedial hypothalamic area in mammals. GnIH neurons project to the median eminence, thus providing a functional neuroanatomical infrastructure to regulate anterior pituitary function. In quail, GnIH inhibits gonadal activity by decreasing synthesis and release of gonadotropin. The widespread distribution of GnIH/RFRP immunoreactive fibers in all animals tested suggests various actions within the brain. In accordance, GnIH/RFRP receptor mRNA is also expressed widely in the brain and the pituitary. GnIH/RFRP immunoreactive axon terminals are in probable contact with GnRH neurons in birds and mammals, and we recently demonstrated expression of GnIH receptor mRNA in GnRH-I and GnRH-II neurons in European starlings. Thus, GnIH/RFRP may also inhibit gonadotropin synthesis and release by inhibiting GnRH neurons in addition to having direct actions on the pituitary gland. Intracerebroventricular administration of GnIH/RFRP further inhibits reproductive behaviors in songbirds and rodents, possibly via direct actions on the GnRH system. The expression of GnIH/RFRP is regulated by melatonin which is an internal indicator of day length in vertebrates. Stress stimuli also regulate the expression of GnIH/RFRP in songbirds and rodents. Accordingly, GnIH/RFRP may serve as a transducer of environmental information and social interactions into endogenous physiology and behavior of the animal. Recently, it was shown that GnIH/RFRP and its receptor are also expressed in the gonads of birds, rodents and primates. In sum, the existing data suggest that GnIH/RFRP is an important mediator of reproductive function acting at the level of the brain, pituitary, and the gonad in birds and mammals